Displays are generally configured by a set of pixels which can reflect transmitted light, or perform a self-luminescent emission/an emission of light. A display that displays an image by reflecting transmitted light is generally referred to as a reflective display. A liquid crystal display, a micro electro mechanical systems (MEMS) type light modulator display using interference, and an electronic paper display using electrophoresis, are examples for the reflective display. In most reflective displays, external light is projected to the display, and an image is provided by using the interference and reflection of the light.
In contrast, the display that displays an image using the emissive effect/self-luminescent effect includes a display that implements the image by using an auxiliary light source formed on a rear surface of the display and a display that provides the image through a self luminescence of light. The former includes, for example, a liquid crystal display (LCD) and a thin film transistor liquid crystal display (TFT LCD), and the latter includes, for example, a light emitting diode (LED) display and an organic light emitting diode (OLED) display.
Meanwhile, although the reflective display provides a clear image when the intensity of the external light is at an appropriate level, it is very difficult to reproduce the image when the intensity of the external light is too strong or too weak, which is problematic in the reflective display. The luminescent/emissive display provides a very clear image having a high visibility when the intensity of external light is weak or there is no light presents outside the display. However, there is a disadvantage in the luminescent/emissive display in that a proper image is not provided because an image of the display itself is buried by the external light when the intensity of external light is strong.
Therefore, various studies are being conducted on a display and the structure of pixels included in the display that can provide a clear image regardless of the intensity of the external light that presents outside the display.